RU1815609C - Method of testing concrete compressive strength - Google Patents

Abstract

Usage: the field of building materials, the study of the strength of concrete in a complex stress state. SUMMARY OF THE INVENTION: The compressive strength of concrete without bending moment is determined. The compressive strength of concrete is determined under the simultaneous action of a moment causing plastic deformation. The compressive force is in a plane different from the plane of action of the bending moment. The coefficient of compression of concrete under the simultaneous action of bending moment is determined by the formula. 1 s.p. f-ly, 1 ill.

Description

The invention relates to methods for testing concrete and provides for the experimental production of a coefficient of concrete working conditions in a difficult stress state.

The purpose of the invention is to determine the coefficient of condition of concrete in compression under the simultaneous action of a bending moment in a plane different from the plane of action of compressive force.

This is achieved by the fact that in the method of testing concrete for compression, which includes loading the sample with bending moment, the compressive strength of the sample is preliminarily determined, loading of the sample with bending moment is carried out until plastic deformations occur, then the sample is compressed until it is fractured by force, is obtained in a plane different from the plane of action of the bending moment, and the coefficient of concrete working condition for compression under the simultaneous action of the bending moment is determined by the formula

  Krazr

 II

ghrazr

R Craer

where L is the coefficient of the condition of the concrete under compression under the simultaneous action of a bending moment in a plane different from the plane of action of the compressive force. Rpaap1 - concrete compressive strength, Rpaap - concrete compressive strength under the simultaneous action of a bending moment, causing plastic deformation.

In addition, the compressive strength of concrete (R) for intermediate values of bending moment is calculated by the formula

R-Rp aaptl O-L) A, Mi1

where M is the effective bending moment, MI1 is the bending moment causing plastic deformation.

The method is carried out using the device shown in the drawing and comprising a hydraulic cylinder 1, a support plate 2 with a cylindrical support

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00

ate about

3

mi, thrust 3. combining a hydraulic cylinder with a base plate, traverses 4 with cylindrical supports, a rod 5 with a ball joint 6, a pump 7 that creates operating pressure in a receiver 8 connected to the pump through a non-return valve 9. The device contains a manometer 10, a press 11 for compressing the sample 12.

The method is carried out as follows.

Lubricate the lower and upper press plate 11.

A support plate 2 is mounted on the bottom plate of the press 11, which is connected to the cylinder 1 by the rods 3 and the beam A, connected by means of the rod 5 to the piston of the hydraulic cylinder 1.

After that, a sample 12 is installed between the base plate 2 and the cross beam 4. Moreover, the sample 12 has a height greater than the height of the base plate 2 and the cross beam 4, which allows transmitting compressive forces to the sample 12, and not to the base plate 2 and the cross beam 4.

Then, using the pump 7 through the receiver 8 with the non-return valve 9, the working pressure in the hydraulic cylinder 1 is created, the rod 5 is set in motion, which through the beam 4 acts on the sample 12 and 1/3 of the span, creating a bending moment in the sample.

When the magnitude of the bending moment, controlled by the pressure gauge 10, causes plastic deformation, press 11 is turned on and the sample 12 is compressed until fracture.

Having experimentally obtained the results of compression testing of the specimen without bending moment Nrazr and the results of compression testing Rpaap under the simultaneous action of the bending moment, determine the coefficient of concrete working condition under compression with the simultaneous action of

5

0

5

0

5

Claims (2)

tensile force and bending moment located in different planes. SUMMARY OF THE INVENTION 1. A method of testing concrete for compression, comprising loading the sample with a bending moment, characterized in that, in order to determine the coefficient of concrete working condition under compression while the bending moment is applied in a plane different from the plane of the compressive force, the strength of the sample is preliminarily determined for compression, loading the sample with a bending moment is carried out until plastic deformations occur, then the sample is compressed until it is destroyed by a force located in a plane other than plane the action of the bending moment, and the concrete work coefficient on compression under the simultaneous action of the bending moment is determined by the formula: RI about II I 1 bit GSR L. - I -------- j ---, Rpaap where L is the coefficient of the condition of the concrete in compression under the simultaneous action of a bending moment in a plane different from the plane of action of the compressive force; R bit I II concrete compressive strength; Rpaap is the compressive strength of concrete under the simultaneous action of a bending moment, which causes plastic deformation. 2. The method according to claim 1, characterized in that the concrete compressive strength R for intermediate values of the bending moment is calculated by the formula M R RP33p 1- (1-L) -f4, M pl. where M is the current bending moment; Mp - bending moment, causing plastic deformation,